cogs/src/run.js

The fast file transform pipeline.

import npath from 'node:path';

import { watch } from 'watchy';

import buildConfig from '#src/build-config.js';
import bustCache from '#src/bust-cache.js';
import getConfig from '#src/get-config.js';

export default async ({
  configPath = 'cogs.js',
  onError = async () => {},
  onEnd = async () => {},
  onResult = async () => {},
  onStart = async () => {},
  watchPaths = []
}) => {
  let building = false;
  let changedPaths = new Set();
  let config;

  const build = async () => {
    if (building) return;

    building = true;

    const paths = changedPaths;
    changedPaths = new Set();
    if (paths.has(configPath)) {
      config = null;
    } else if (config) {
      await Promise.all(
        Array.from(paths).map(path => bustCache({ config, path }))
      );
    }

    if (!config) config = await getConfig(configPath);
    await onStart();
    await buildConfig({
      config,
      onResult: async result => {
        const { didChange, targetPath } = result;
        if (didChange) await bustCache({ config, path: targetPath });
        return onResult(result);
      }
    });
    await onEnd();

    building = false;

    if (changedPaths.size) await build();
  };

  if (!watchPaths.length) return build();

  const tryBuild = async () => {
    try {
      await build();
    } catch (er) {
      await onError(er);
    }
  };

  const handleChangedPath = paths => {
    for (const path of paths) changedPaths.add(npath.relative('.', path));
    tryBuild();
  };

  const closeWatcher = watch({
    onChange: handleChangedPath,
    patterns: [].concat(configPath, watchPaths)
  });

  await tryBuild();

  return closeWatcher;
};